StarterSamle.cs

[FunctionName("RegistOrder")]
public static async Task<HttpResponseMessage> RegistOrder(
    [HttpTrigger(AuthorizationLevel.Function, "post", Route = "order")]HttpRequestMessage request
    ,[OrchestrationClient]DurableOrchestrationClientBase client)
{
    var input = await request.Content.ReadAsStringAsync();
    var instanceId = await client.StartNewAsync("OrderRegistOrchestrator", int.Parse(input));
    return client.CreateCheckStatusResponse(request, instanceId);
}